Abstract: A system and method of operating a database system to protect personal identifiers from being revealed. The system and method obfuscates personal identifiers using a secret value, storing in a database records containing the obfuscated personal identifier, storing the secret value in a identifier translation device, receiving at a request preparer a record request identifying a requested record using a non-obfuscated personal identifier, and operating the request preparer to direct the identifier translation device to translate the non-obfuscated personal identifier into an obfuscated personal identifier using the secret value stored in the identifier translation device and using the obfuscated personal identifier in a query to the database.

Abstract: A system and method of operating a database system to protect personal identifiers from being revealed. The system and method obfuscates personal identifiers using a secret value, storing in a database records containing the obfuscated personal identifier, storing the secret value in a identifier translation device, receiving at a request preparer a record request identifying a requested record using a non-obfuscated personal identifier, and operating the request preparer to direct the identifier translation device to translate the non-obfuscated personal identifier into an obfuscated personal identifier using the secret value stored in the identifier translation device and using the obfuscated personal identifier in a query to the database.

Abstract: A magnetic writing and optical reading head for a magnetic data carrier including at least one optical focusing device (SOI.sub.1, SOI.sub.1) for focusing a beam of light onto the carrier, and a magnetic writing transducer (TMI.sub.1, TMI.sub.2) disposed on the same rail (PI.sub.1, PI.sub.2) of the head as the optical device. According to the invention, the head is characterized in that the optical device and the transducer are disposed in the immediate vicinity of one another at a distance d less than the ratio of the difference between the width of the track L.sub.p and the diameter D of the beam of light produced by the device (SOI.sub.1, SOI.sub.2) to twice the sine of the maximum azimuth angle .psi..sub.M. The invention is applicable to magnetooptical disk memories.